Aceh is celebrated for its opposition to foreign domination. Its very identity as a sultanate was based on resistance to the Portuguese in the 16 th century, and to Dutch, English and French in the 17th and 18th. In the 19th century the sultanate again provided the last and fiercest resistance to the Dutch advance, and in the 20 th to Jakarta. Aceh's long-standing relationship with Ottoman Turkey, however, provides a startling contrast. The readiness of Acehnese sultans in the 16th and 19th centuries to declare themselves subjects, even 'slaves', of the Ottoman sultan was a tactical device to attract the Turks and deter the Europeans, but also reflected a world-view that the house of Islam should be united under a Caliph, and should resist rule by non-believers. Aceh's declared "vassalage" to the Ottomans had deep roots in the 16th century, but only in the 19th were attempts made to translate these into the language of modern empire and sovereignty. Ottoman documents now allow us to add the Aceh-Turkey relationship to our understanding of Indonesia's history.